Yes an OBC certificate issued by the West Bengal government is valid for central government PSU provided your cast is listed as OBC by the central government as well.
You must first verify whether your caste comes under OBC according to eligibility requirement under rules applicable to Central Government Jobs.
If you are applying for any government job then you must have the caste certificate issued by the Union/Central Government of India because when recruitment notification issues by any authority or department as Bank, Railway, Insurance, SSC etc. then authority provide a format of Caste Certificate for SC/ST and OBC category candidates so you have to print that format and go to the office of the Magistrate or SDM – Sub Divisional Magistrate or Collector of your district and apply for a new certificate of Central Government of India then they will provide you a fresh Caste Certificate that will be issued under the norms of Central Government of India and you can show this certificate in any type of government job recruitment all over India.
But sometimes state government recruits candidates for various departments and does not demand for the Cast Certificate issued by Central Government where you can submit the Caste Certificate issued by State Government and that will be eligible and as per the norms.